The Low-Mass End of theMBH/MhostRelation in Quasars

摘要

TheMBH-Mhostrelation in quasars has been probed only in a limited parameter space, namely, atMBH~109 M⊙andMhost~1012 M⊙. Here we present a study of 26 quasars laying in the low-massend of the relation, down toMBH~107 M⊙. We selected quasars from the SDSS and HST-FOSarchives, requiring modestMBH(as derived through the virial paradigm). We imaged our sources inHband from the Nordic Optical Telescope. The quasar host galaxies have been resolved in 25 outof 26 observed targets. Host galaxy luminosities and stellar masses are computed, under reasonableassumptions on their star formation histories. Combining these results with those from our previousstudies, we manage to extend the sampled parameter space of theMBH-Mhostrelation in quasars. The relation holds over 2 dex in both the parameters. For the first time, we are able to measure the slope of theMBH-Mhostrelation in quasars. We find that it is consistent with the linear case (similarly to what observed inquiescent galaxies). We do not find any evidence of a population of massive black holes lying belowthe relation.